1. Field of the Invention
The invention generally relates to ammunition making. More specifically, the invention relates to firearm cartridge casings and to finishing operations. Especially in the practice of single stage or progressive ammunition loading and reloading, an improved implement checks the length of a case while conducting another step such as filling, resizing, or reconditioning.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
Spent firearm cartridge casings, referred to as cases or brass, often can be reused by reloading. The reloading process involves a series of basic steps, including sizing the case, decapping, priming, powder charging, and seating a new bullet. Some of these steps can be combined or separated into several sub-steps. Additional steps can be performed and may be required with specialized types of cases. These steps and variations of them can be performed either by hand or by machine. A single stage or multistage mechanical press, sometimes called a reloading press, is a useful aid to performing these steps.
A multistage press, such as a progressive, multi-station reloading machine can perform the required steps by incrementally processing a case through an indexed series of workstations. A different die or tool is located at each workstation and performs a processing step on a case when the case is present at the workstation. Commonly, the workstations are arranged in a circle on a tool platform. Such a reloading machine employs a turret or rotary conveyor to carry a series of cases from workstation to workstation.
The rotary conveyor or shell plate defines a plurality of conveyor stations, each adapted to carry a case. The conveyor stations are spaced apart similarly to the workstations, so that the shell plate can be stopped at index points at which each workstation is aligned with a conveyor station. With a case carried in a conveyor station, the shell plate rotates in a parallel circle on a common axis to the workstation circle. When stopped at the index points, the shell plate can be elevated toward the tool platform, thereby raising the carried case toward the die at the workstation to engage the case in the die. Subsequently, the shell plate lowers to remove the case from the die.
The dies or other tools are carried on the tool platform or tool head in a circular array. Commonly, the tool platform provides a threaded bore at each workstation. A die or other tool is installed at a workstation by threading it into the appropriate threaded bore. Each die is adjusted to process a size or length of case by adjusting how deeply the die is threaded into the tool platform. In some instances, the workstation where a die or tool might be installed is chosen from several candidates, while other dies or tools must be installed at a specific workstation or in a specific sequence.
The tools installed at the various workstations perform the required functions in various combinations and with additions or modifications accounting for the different numbers of stations. For example, the reloading machine shown in U.S. Pat. No. 4,163,410 to Dillon provides eight stations. Seven of these stations have distinct functions, which are: inserting the shell into the machine, sizing the case and decapping to remove the spent primer, swaging the primer cavity, seating a new primer, belling the case and loading a powder charge, seating a new bullet, and removing the reloaded shell from the machine. This patent also discloses a powder dispenser that operates by causing a powder bar to slide in response to elevation of a shell case into the powder charging workstation.
Processing steps such as inserting and removing the case from the rotary conveyor may be performed manually or may employ inserting or removing mechanisms operating from a position other than the tool head, such as from a side of the case or the side of the rotary conveyor. Inserting and removing a case from the conveyor may take place other than at an index point.
The reloading machine shown in U.S. Pat. No. 4,343,222 to Dillon provides four stations. The first station combines inserting a spent shell into the machine, sizing the shell in a sizing die, decapping with a decapping pin, and seating a new primer. The second station loads a powder charge into the shell. The third station seats a bullet into the shell. The fourth station crimps the shell. The completed shell then advances to the first station for a second time, where it is removed from the machine before another spent shell replaces it on the rotary conveyor. This reloading machine employs a swinging toggle linkage for elevating the rotary conveyor or turret that carries shells between workstations.
Reloading machines with five stations are sold commercially. The technology of operation is similar to that described in the aforementioned patents to Dillon. The functions of the five stations can be: sizing, decapping and priming; powder charging; powder checking; seating a new bullet; and crimping. Inserting and removing the cases is automated and takes place at separate positions, before the first and after the last workstations.
In a progressive reloading machine that employs a tool head with dies or tools carried in a circular pattern, the tool head often is mounted at the top of a frame. The rotary conveyor or shell plate that carries the cases is mounted to the frame below the tool head, on a concentric axis to the circle of tool head bores. The shell plate carries cases with their open end facing up, toward the tool head. The shell plate clips to the base of each case so that the shell plate can both push and pull the cases without separating from the cases.
Some progressive reloading machines operate similarly to a manually operated press. A manually operated lever and crank mechanism elevates the rotary conveyor and all carried shell cases toward the tool head, such that the cases longitudinally engage the dies or tools at the various workstations of the tool head. This longitudinal engagement of cases and dies causes the dies to perform their corresponding functions on the respective engaged cases. Thus, a step of the reloading process takes place at each of the workstations, as respective cases are decapped, primed, charged with powder, and seated with a bullet.
The lever and crank mechanism then is moved in reverse direction to lower the rotary conveyor and its carried cases and to cause the shell plate to advance to the next index position. Thereafter, the sequence is repeated as necessary to process each shell case at each workstation. A lever and crank mechanism for a reloading machine is known from U.S. Pat. No. 4,522,102 to Pickens.
While elevating the conveyor is the common practice, equivalently the tool head could be lowered toward the conveyor to engage the shell cases in the dies or tools at the respective workstations and to thereby perform the respective reloading steps. In such a reversed operation, the tool head must be raised to disengage from the shell cases before the rotary conveyor advances to the next index point.
U.S. Pat. No. 3,483,792 to Williams shows a progressive reloading machine that lowers the tool head instead of raising the turret. In addition, the Williams patent shows six work stations, where the reloading tasks are divided into loading the shell case into the turret, depriming, belling the case mouth and inserting a new primer, loading a powder charge, seating a bullet, and removing the shell from the turret.
Because reloading typically is practiced on used shell cases, initially the cases are deformed such that they do not meet size specifications. Not all cases can be reused. Even after a single firing, some cases are ruined beyond reclamation.
The problem of reforming a spent cartridge case during reloading is partially met by use of a sizing die. Often the first step in reloading is to insert a case longitudinally into a sizing die. Often the sizing die is combined with a decapping pin. Thus, in a progressive or multi-station press, the first workstation after a case is loaded into the shell plate should carry the sizing die. The sizing die will reform the case both from the outside and from the inside. A cavity in the die is suitably shaped to reform the exterior profile of a case to specifications, at least as to maximum sidewall diameter and diametric contour. An expander ball carried on the centerline of the die cavity enters the case mouth to expand the mouth to specified size. Subsequently, when the shell plate is lowered, the case is pulled free of the cavity and of the expander ball. U.S. Pat. No. 5,635,661 to Tuftee shows such a sizing die with internal expander ball.
A sizing die is not always able to restore a case to specified length. If a case is too short, typically it cannot be reused because there is no economical way to lengthen such a case. A case that initially is too long possibly can be restored to specified length. However, the stroke of a reloading machine is fixed or at least is poorly adapted for adjustment to the sizing requirements of each individual spent case.
Machines for trimming long cases independently of a reloading press are known, as shown in U.S. Pat. No. 6,101,915 to Sinclair and U.S. Pat. No. 4,813,827 to Dugger. These trimmers are not suited for use in a progressive reloading machine. However, U.S. Pat. No. 5,309,813 to Henley proposes a power operated resizing die combined with a case length trimmer, in a form factor adapted for use with a progressive reloading machine.
A sizing die offers length adjustment to coordinate with the stroke of the reloading machine. Such adjustment typically is a batch adjustment that takes into account the maximum length specification for the size of cartridge case being reloaded. The depth of the sizing die in the threaded bore of the tool platform can be set by trial and error, by processing sample cases from the batch and then measuring the resulting cases after they are removed from the reloading press. Measurement tools typically are independent of a reloading press. United States patents that disclose an independent case length measurement tool include: U.S. Pat. No. 4,918,825 to Lesh and U.S. Pat. No. 5,570,513 to Peterson. Some sizing dies offer length gradations on a threaded adjuster to reduce the amount of trial and error. U.S. Pat. No. 6,397,720 to Fox et al shows a sizing die with measurement markings on an adjuster.
Sizing dies inherently introduce error into the determination and adjustment of case length. Substantially every known sizing die suited for use with a reloading machine relies upon longitudinal withdrawal of the case from the die. Even a sizing die with built-in trimmer, such as taught in the Henley patent, suffers the introduction of inaccuracy when the sized and trimmed case is longitudinally withdrawn from the die. Friction from the die on the external surface of the case, and friction from the expander ball on the internal surface of the case, can lengthen the case by an unknown and unpredictable amount.
Shell cases are lubricated prior to processing in a reloading machine. Lubricant properties differ. The use of different lubricants might result in variations of length as cases are sized.
Even new brass cases vary in configuration, which would be expected in a mass produced product. After a cartridge has been fired, the residual configuration and characteristics of a spent brass case will be still more unique and individual. The frictional interaction between any one spent case and a sizing die can be uniquely different than with a different spent case. For these reasons, the practice of adjusting headspace in a sizing die by using a few test cartridge cases does not necessarily produce an accurate result with any other cartridge case.
Pistol ammunition encounters another source of error during reloading. The case mouth must be belled before the new bullet is seated. The belling step can be performed at any station before the new bullet is applied and seated. Some reloading machines perform the belling step in combination with recharging the case with powder. At a single workstation, the case is elevated against a powder funnel, where the case then raises the powder funnel, triggering the release of a powder charge that drops into the case. For pistol ammunition, the contact end of the powder funnel is configured to bell the case mouth. The rising case raises the powder funnel until the powder funnel strikes a stop. The case rises further, belling the case mouth against the stopped powder funnel. The belled and recharged case then is lowered from the powder funnel. The belling step introduces another opportunity for the case length to change in an unpredictable manner.
The practice of reloading cartridge cases often is motivated by reasons of economy. Clearly it would desirable to identify defectively sized cases as early as possible in the reloading process, before investing needless materials in a cartridge that cannot be used. A key stage in reloading is the seating of the new bullet. When the bullet has been seated, the bullet and powder charge no longer can be safely salvaged from the cartridge. Thus, the cost of the reloaded cartridge has been fully committed. Removing a bullet from a live cartridge is dangerous. Despite the danger, people have tried to disassemble and salvage a fully reloaded cartridge. If for no reason other than to reduce this type of salvage effort, it would be desirable to identify defectively sized cartridges before the bullet is seated.
Cases that are longer than a specified limit are unsafe to use. A reloading machine will push such an overly long case too far forward onto the powder funnel or other belling device. As a product of the excess movement, the brass becomes crimped at the open end. The crimped brass might dig into the bullet and restrict the bullet from clean separation when fired. As a result, the case might fail, presenting a danger to the shooter and possibly damaging the firearm.
A progressive reloading machine offers the advantages of automation to the task of reloading a large number of cartridges. It remains possible to measure every case before seating the bullet by using an independent measuring tool such as those disclosed in the Lesh and Peterson patents. However, use of these tools would require that the case be removed from the progressive reloading machine before performing the bullet-seating step. This interruption of the progressive reloading cycle would defeat the purpose of having such a machine. Therefore, it would be desirable to identify a case having improper length both while the case remains in the progressive reloading machine and before the bullet-seating step.
A single-station reloading machine can perform the same steps as a progressive reloading machine, but done one tool or one step at a time. A first tool might be used to process an entire collection of cases, after which a second tool replaces the first and processes the entire collection of cases, and so on. A significant difference is that only one workstation is present on the single-station tool platform. Of course, the single-station reloading machine does not benefit from an indexing rotary conveyor system that moves the cases from workstation to workstation, as in a progressive reloading machine. Even a single-station reloading machine would benefit by a reduction in the number of tool changes by the combination of several functions into one tool or one step. For example, it would be beneficial to combine case length checking with another function, such as powder loading or powder level checking. Therefore, from the perspective of a single-station reloading machine, it would be desirable to combine case length checking with another function to be performed at one time.
To achieve the foregoing and other objects and in accordance with the purpose of the present invention, as embodied and broadly described herein, the method and apparatus of this invention may comprise the following.